Antimicrobial therapy:Inhibit Bacterial Cell Wall Synthesis

Penicillin

• MOA: Activate bacterial autolysins to digest peptidoglycan cell wall & inhibits transpeptidase (cross-links peptidoglycan molecules to form a rigid cell wall)

• Bactericidal against gram + organisms

• Beta lactam ring

• Penicillin G- given IM or IV, narrow spectrum, active against mostly  gram+ organisms, used for pneumonia and meningitis 

  • Least toxic of all antibx

  • Penicillin ALLERGY (cross-sensitivity to other beta lactam)

• Resistance: via beta-lactamase (cleaves beta lactam ring → inactivates drug)

Cephalosporins

• Bactericidal

• Beta lactam ring

• 1st gen→ 5th gen

  • 5th generation: covers wider range of bacteria (gram + and -), increased beta lactamase resistance (can function against antibx resistant bacteria)

• Adverse Effects:

  • Abdominal pain, nausea, vomiting, diarrhea– take with food 

  • Superinfections such as C diff

  • Allergic reactions- anaphylaxis or maculopapular rash (Cross allergy with penicillin)

  • Nephrotoxicity– monitor renal function

  • If given IM or IV, risk for thrombophlebitis and abscess formation

  • Alcohol intolerance

Carbapenems

• Beta lactam structure

• Resistant to beta lactamases (resistant to resistance)

• Very broad spectrum

• Administered IV or IM (never PO)

• Indicated in tx of serious CNS infections

• Adverse effects:

  • GI, Hypersensitivity, Superinfection, seizures (renal dysfunction)

• Excreted by kidneys – monitor renal function

Vancomycin

• No beta lactam ring

• Used for serious infections only with gram + bacteria such as C diff and MRSA

• Toxicity→ renal failure

• Ototoxic

• Vancomycin Infusion Syndrome– SLOW infusion and dilute solution

• Thrombophlebitis

• Immune-mediated thrombocytopenia

• Must be given IV unless for C diff

• Avoid extravasation – may cause necrosis